The Postal Service blamed the deeper losses on the recession and on the continuing growth of e-mail. A change in the interest rates affecting the Postal Service's workers' compensation liability also played a role, the organization said.

Chief Financial Officer Joe Corbett said the losses were worsening despite cuts that generated cost savings of $9 billion over the past two years. Those savings came primarily from the elimination of 105,000 full-time positions -- "more than any other organization, anywhere," Corbett said.

As more communications go electronic, mail volume keeps dropping. The Postal Service delivered 170.6 billion pieces in its 2010 fiscal year, compared to 176.7 billion pieces the prior year. That decline cost the service around $1 billion in lost revenue.

"We will continue our relentless efforts to innovate and improve efficiency," Corbett said. "However, the need for changes to legislation, regulations and labor contracts has never been more obvious."

Postal Service spokeswoman Joanne Veto said her organization has asked Congress to allow it to scale back to five-day delivery, cutting Saturdays, and to discontinue its "unique" requirement to pre-fund its retirement fund -- something no other federal agency is required to do.

Congress has taken no action on these requests, she said.

Auditor Ernst & Young is expected to issue an audit opinion saying that "questions remain" about the Postal Service's ability to make its $5.5 billion pre-funding payment for retiree health benefits, due at the end of fiscal year 2011.

Despite that, Veto said the Postal Service is "fully funded for existing retirement benefits."

Veto also said that mail volume is expected to pick up in fiscal year 2011, although first-class mail -- the service's most lucrative product -- is forecast to continue its decline.